Effect of petrochemical sludge concentrations of changes in mutagenic activity during soil bioremediation process.

The present study was performed to assess the effect of the petrochemical sludge application rate on the mutagenic activity (Ames test) of soil and the persistence of mutagenic activity during laboratory soil bioremediation process. Sludge-soil systems were prepared at four different sludge application rates (1.25, 2.5, 5, and 10% w/w). Unamended soil was used as a control. Immediately following sludge application, in the absence or presence of S9, a linear correlation between sludge application rates and mutagenicity was found but differed significantly (p < 0.05) from the control system only at higher application rates (5 and 10% w/w). The direct mutagenicity of all systems decreases during the bioremediation process, and after a year of treatment only the 10% system induced a mutagenic response that was significantly different from the control system. On the other hand, an initial increase of the indirect mutagenicity was observed at all application rates. The time required for observing this increase was inversely proportional to the initial sludge concentration. After a year of treatment, the indirect mutagenicity of all sludge-amended soils was not significantly different but was significantly different from the unamended soils. The persistence of the direct mutagenic activity of the sludge-amended soils was related to the sludge concentration, whereas the indirect mutagenic persistence was related to the relationship between easily degradable hydrocarbons and polynuclear aromatic hydrocarbons concentration and independent from the initial application rate.

Bio-remediación como alternativa a la incineración de residuos con hidrocarburos aromáticos polinucleares

Se presenta la aplicación de un esquema de ensayo de tratabilidad en tres niveles para evaluar y diseñar una técnica de bio-remediación para el tratamiento de barros de fondo de separadores API con un alto contenido de hidrocarburos aromáticos polinucleares generados en el polo petroquímico Ensenada. El esquema de trabajo permite definir los requerimientos de adecuación de sitio, el plan de operaciones, el plan de monitoreo y establecer los tiempos de tratamiento. Esto resulta fundamental para poder definir la estructura de costos que sera la que en definitiva permita comparar la bio-remediación con la incineración

Técnicas de bio-remediación: ensayos de tratabilidad: nivel II

Se desarrollan tres sistemas para el estudio de tratabilidad de dos residuos industriales con claros indicios de tratabilidad a nivel 1. Se evaluó la influencia de la carga, temperatura, presencia de materia orgánica y pérdida por volatilización. La mutagenicidad y el efecto tóxico sobre semillas manifestaron aumentos significativos durante los ensayos, posteriormente, descendieron a valores aceptables. La eliminación de hidrocarburos fue principalmente atribuida a procesos biológicos. Los ensayos permitieron evaluar los distintos aspectos de diseño y determinar las variables mas relevantes que deberían ser monitoreadas en los ensayos de nivel III

Assessment of the toxic potential of hydrocarbon containing sludges.

A short-time period microbial toxicity test-battery was used for the investigation of acute toxicity and genotoxicity of five hydrocarbon containing sludges. Four sludges were obtained from a petrochemical industry and the fifth from a petroleum refinery. Some of the sludges had been stored for long periods. Bioremediation potential assays for soils polluted with each of the sludges were also considered. The sludges did not show acute toxicity in any of the microbial tests performed. However, when the diethylether soluble fractions of these sludges were analyzed some of them showed acute toxicity, for which the clearest results were obtained with the resazurin reduction method. The greatest toxicity detected with the Resazurin based method was found in the diethylether extracts of the freshly collected (not stored) sludges. On the other hand, the diethylether soluble fraction of those sludges that had been stored showed genotoxicity when analyzed with the Salmonella/microsome assay. After the incorporation of the sludges into the soil, increased bacterial counts were noted and substantial hydrocarbon elimination was achieved in 30 days, showing that bioremediation may be a possible technology for cleaning soils polluted with these sludges.

[Storage of hydrocarbon-degrading bacteria]. / Conservación de bacterias degradadoras de hidrocarburos.

The storage in the laboratory of hydrocarbon degrading bacteria to be used in the decontamination of polluted sites or in the enhancement of biological treatment of industrial effluents was studied. Storage was carried out at 4 degrees C in nutrient agar and in a medium with selection pressure, liquid mineral medium with hydrocarbons. Storage at 4 degrees C with selection pressure and storage at -20 degrees C of 7 gram negative bacilli were compared. The former was the easiest method for preserving the greatest number of strains viable and active.

Conservación de bacterias degradadoras de hidrocarburos. / [Storage of hydrocarbon-degrading bacteria]

The storage in the laboratory of hydrocarbon degrading bacteria to be used in the decontamination of polluted sites or in the enhancement of biological treatment of industrial effluents was studied. Storage was carried out at 4 degrees C in nutrient agar and in a medium with selection pressure, liquid mineral medium with hydrocarbons. Storage at 4 degrees C with selection pressure and storage at -20 degrees C of 7 gram negative bacilli were compared. The former was the easiest method for preserving the greatest number of strains viable and active.

Conservación de bacterias degradadoras de hidrocarburos / [Storage of hydrocarbon-degrading bacteria]

The storage in the laboratory of hydrocarbon degrading bacteria to be used in the decontamination of polluted sites or in the enhancement of biological treatment of industrial effluents was studied. Storage was carried out at 4 degrees C in nutrient agar and in a medium with selection pressure, liquid mineral medium with hydrocarbons. Storage at 4 degrees C with selection pressure and storage at -20 degrees C of 7 gram negative bacilli were compared. The former was the easiest method for preserving the greatest number of strains viable and active.

[Isolation of antibiotic-resistant Escherichia coli from the water of the Río de la Plata]. / Aislamiento de Escherichia coli resistentes a antibióticos a partir de aguas del Río de la Plata.

Water of a recreational zone of the Río de la Plata was analyzed. Levels of total heterotrophic bacteria ranged from 1.5 x 10(3) to 6.2 x 10(3) CFU/ml and total coliforms were between 5.0 x 10(2) and 7.0 x 10(3) per 100 ml. Values of fecal coliforms were between 1.0 x 10(2) and 1.3 x 10(3) per 100 ml. Among 131 E. coli strains isolated, 20.6% of cephalothin resistance was found, followed by nitrofurantoin, ampicillin, sulfisoxazole and the trimethoprim sulfamethoxazole combination. Resistance to more than one antibiotic was found in 36.7% of the strains isolated and 9.2% were resistant to three or more antibiotics. Three strains resistant to four antibiotics and one resistant to five were isolated. The highest percentage of combined resistance occurred for the pairs cephalothin-nitrofurantoin and cephalothin-ampicillin.

Aislamiento de Escherichia coli resistentes a antibióticos a partir de aguas del Río de la Plata. / [Isolation of antibiotic-resistant Escherichia coli from the water of the Río de la Plata]

Water of a recreational zone of the Río de la Plata was analyzed. Levels of total heterotrophic bacteria ranged from 1.5 x 10(3) to 6.2 x 10(3) CFU/ml and total coliforms were between 5.0 x 10(2) and 7.0 x 10(3) per 100 ml. Values of fecal coliforms were between 1.0 x 10(2) and 1.3 x 10(3) per 100 ml. Among 131 E. coli strains isolated, 20.6

of cephalothin resistance was found, followed by nitrofurantoin, ampicillin, sulfisoxazole and the trimethoprim sulfamethoxazole combination. Resistance to more than one antibiotic was found in 36.7

of the strains isolated and 9.2

were resistant to three or more antibiotics. Three strains resistant to four antibiotics and one resistant to five were isolated. The highest percentage of combined resistance occurred for the pairs cephalothin-nitrofurantoin and cephalothin-ampicillin.

Aislamiento de Escherichia coli resistentes a antibióticos a partir de aguas del Río de la Plata / [Isolation of antibiotic-resistant Escherichia coli from the water of the Río de la Plata]

Water of a recreational zone of the Río de la Plata was analyzed. Levels of total heterotrophic bacteria ranged from 1.5 x 10(3) to 6.2 x 10(3) CFU/ml and total coliforms were between 5.0 x 10(2) and 7.0 x 10(3) per 100 ml. Values of fecal coliforms were between 1.0 x 10(2) and 1.3 x 10(3) per 100 ml. Among 131 E. coli strains isolated, 20.6

of cephalothin resistance was found, followed by nitrofurantoin, ampicillin, sulfisoxazole and the trimethoprim sulfamethoxazole combination. Resistance to more than one antibiotic was found in 36.7

of the strains isolated and 9.2

were resistant to three or more antibiotics. Three strains resistant to four antibiotics and one resistant to five were isolated. The highest percentage of combined resistance occurred for the pairs cephalothin-nitrofurantoin and cephalothin-ampicillin.

Use of selected autochthonous soil bacteria to enhanced degradation of hydrocarbons in soil.

A mixed population of soil hydrocarbon degrading bacteria was used to accelerate the biodegradation of a petrochemical waste. An aromatic hydrocarbon storage tank bottom was mixed with soil (10% w/w). After a month 43% of the hydrocarbons were degraded in uninoculated and in fertilized soil, while 65% were degraded in inoculated soil. Nutrient supplemented vermiculite seems to be a good possibility to produce effective hydrocarbon degrading inoculants.